Trailer brake



Feb. 13, 1940. L. H. PELsTER TRAILER BRAKE Filed Feb. 11, 1939 3Sheets-Sheet 2 I Patented Feb. 13, 1940 UNITED 'STATi. fsI y PATENTOFFICE;

` TnAiLER BRAKE i Lester H. Pelster, Newv Haven, Mo.` 4 ApplicationFebruary 11, 1939, lserial N0. 255,986

This invention relates to brakes of the -hy-` draulic'type especiallyadapted for; motor vehicle trailers and has for the primary object theprovision of a device of this character which will be extremelyefficient employing the rotation of the wheels of `the trailer for the`operation of fluid pumps for the circulation ofthe fluid underpressure,` the circulation of said yuid being under manual controlwhereby the resistance ofthe l0 back pressure of the fluid on said pumpsmay be increased and decreased for varying the braking action `on thetrailer` wheels'through said pumps along with means under manual controlwhereby the pumps may be rendered operative and inopera-tive as desiredand when inoperative allowing the trailer wheels to rotate freely of anydrag.

With these and other objects in View, the in `vention consistsin certainnovel features of construction, combination and arrangement of parts tobe hereinafter more fully described and claimed. y l.

For a complete understanding of my invention, reference is to be had tothe following description and accompanying drawings, in which .2325yFigure l is a topplan View illustrating a trailer brake constructed inaccordance withiny invention.. I f Y Figure 2 is a sectional view takenon thel line 2-2 oi Figure l illustrating the arrangement of4 30thepurnps and the operatingmeans therefor.

Flgure is a `sectional Viewy taken onthe line 3-3 of Figure 1 showing4one of the means for rendering the pumps operative and inoperative. i

Figure 4 is a vertical sectional Viewishowing the means of renderingthepumps operative and y inoperative andalso showingintake and exhaustvalves for the pumps vand the means of operating said valves. i t l t'40 t Figure 5is`a detail sectional View showing one of thecams foroperating one of the valves.

Figure 6` is a fragmentary perspective "view showing one end of one. ofthebrake bands.

Infthe drawings, `the numeral 5 indicates a housing including oppositelyextending tubular sleeves 6 in which `axles lare journaledand a medialcasing-like portion 8. Theaxles 1 are a pair of` axles employed on atrailer commonly towed behind a motor Vehicle (not shown). g The axles 1areof the type 'on which the trailer wheels may` besecured. The adjacentends of the tubu-A lar sleeves are supported by gear casings S securedon opposite sidesofthe portion 8. The axles 'I` extend into thegearcasingsand also the ends I0 of a crankshaft; Il ljournaled in the of thedrums.

3 claims; (01.138-9'1) v K portionr 8 of the housing. Pairs of bevelgears I2 operate in the vgear ca'sings and one gear of each pair ofgears are'secured to the axles 'I bysplined connections whilethe otherbevel gears of said pairs of gears are vsplined on the ends I0 of the 5crank shaftY I Spider gears I3 `mesh with the pairs of bevel gears andsaid spider gears are journaled on stub shafts I4 carried by drumsflwhich surround the pairs of bevel gears I2 and supported thereon by the"spider gears. gearing larrangement under normal conditions willpermitthe axles 'l to turn free of the crank f sliaftll. "-Y l However', whenthedrums I5 `are gripped'a'nd held then the rotation of theaxles l' willbring 16 about rotation of the crank shaft Il.

`Surrounding the drums Iare split brake bands IB having forked ends I1to slidably and rotat- `ably receive band `operating rods I8 rotatablyand slidablymounted in the gearxcasings 9' and to lo which are securedoperating `arms I9. Coil springsare mounted on the rods `I8 between theforked .ends of the brake bands and act on said ends for the purposeiofexpanding the bands free bers 2t are threaded in theg'ear casings 9 andslidablyv receive the rods I awhile said `rods are alsosupported bybearings 2| forming a part of the gear casings The bearingsl have camfaces' 22 which-coact withcanis 23 secured. on 30 saidrods It wherebyrotation of the rods in one direction will bring about contraction ofthe bands on the drums and a rotation of the rods i8 in an oppositedirection will permit'the springsto expand the bands away from thedrums;` f 35 The operating arms I9 are pivotally connecte as shown at`2t to piston "stems 'of a hydraulic medium 23 mounted on the casing 5or the'portion 8 thereof. The medium 23 is similar in construction to ahydraulic brake booster, as for in- 40 the brake bands on the drumszasdesired.` `It is 50 to be understoodthat the brake `bands are merely forholding thedrums against rotation and when said drums areheldagainstrotation the crank shaft is driven bythe rotation ofthe axles 1.

l ,Series of pumps Mare mounted ontherportion This `lo Sccketed'screwthreaded mem- 25` iii ' pumps.

sages to said cylinders.

8 of the casing 5 and each consisting of a cylinder having communicationwith the interior of the portion 8 of the casing, and in which operatesa piston 26, the connecting rod 21 thereof being coupled as customary tothe crank of the crank shaft Il. Thus it will be seen that rotation ofthe crank shaft brings about reciprocation of the pistons in thecylinders. Each cylinder has an intake passage 23 and an exhaust passage29. vIntake and exhaust valves Sli and 3l control ythe intake andexhaust pas- The valves and 3l are urged in engagement with their seatsby springs 32 and are engaged by push rods: 3d slidable in .bearingsprovided therefor in the casing and are actuated by cams35 secured onthe crank shaft. The valves are so timed that during the suction strokeof the piston the intake valve is opened and the exhaust valve closedand on the compression stroke of the piston the intake valve is closedand the exhaust valve is opened. y

Connected to the intake passages 2S is a iiuid intake pipe 3G extendingfrom the bottom of the portion 8 of the casingl 5. 'It is to beunderstood that a large quantity of uid is placed in the portion il ofthe casing so that on the suction strokes of the pistons the fluid willbe drawn into the cylindersand expelled therefrom on the compressionstrokes ofthe pistons into the exhaust passages which are in turnconnected to an exhaust pipe 3l, the outlet of which is connected to acylinder 38 having a series of ports or perforations 33 controlled by aplunger type valve et, the stem of which is indicated by the characteril and extends into a casing i2 mounted on the portion 8 of the casingor housing 5. The casing 42 is in the form of a cylinder and the stem 4lhas secured thereto a piston 43. A

' coil spring acts on the piston 4.3 to drive the sameV in the directionof one end of the casing orcylinder d'2 to which end is connected a uidpipe 615. This fluid pipe extends to a fiuid source and has accntrolvalve therein. Normally, the spring lill positions the valve illso asto uncover the ports 39 to allow the fluid circulated by thepistons 26 of the pumps to escape substantially freely into the'portionof the housing 5. However, When iiuid pressure is applied to the pistont3, the valve Iltis rnc-ved to gradually close the ports t9 therebygradually stopping the exhaust of fluid from the pumps and consequentlycreating a back pressure on the pistons of the The resistance of theback pressure on the pistons brings about braking action on the wheelsoi' the axles 'l consequently slowing down or stopping the trailer.

In operation, tov brake the trailer, the operator of the motor vehicleto which the trailer is coupled operates the control of the medium 23 tobring about contraction of the bands on the brake drums I5 rtherebyestablishing adrive between the axles 'i of the trailer and the crankshaft. The rotation of the crank shaft by the axles reciprocates thepistons bringing about a circulation of iiuid through the pumps into theexhaust pipe. The operator then actuates the control for the movement ofthe piston 'i3 to bring about closing of the ports 39 by the Valve :illstopping they escape of fluid from the pumps. The pumps continuing tooperate build up a resistance of iiuid pressure in the exhaust pipe andthis resistance against'thc pistons of the pumps brings about braking.actionon the axles and consequently the wheels of the trailer.v Thisbraking action on the Wheels of the trailer can be as gradual and asrapid as desired by the operator bringing about a gradual closing orrapid closing of the ports 39 by the amount of fluid pressure permittedto act on the piston 43. As soon as the uid pressure is reduced orrelieved on the piston 113, the spring 44 positions the valve to opentheports 39 relieving the back pressure of the fluid on-the pistons of thepumps, consequently stopping the braking action on the trailer Wheels.The operator then, through the mediurriv 23 and its control, frees thebrake'bands I6 of the drums l5 and interrupts the drive between theaxles and the crank shaft thus allowing the axles to rotate freely fromany drag from the pumps.

It is believed that the foregoing description, when taken in connectionwith the drawings will fully set forth the construction and advantagesof this invention to those skilled in the art to which such devicerelates, so that further detailed description will not be required.

Having described the invention, what I claim l. In a fluid brake, a.housing including a fluid chamber and axle sleeves to receive axles ofground wheels, a crank shaft journaled in said housing, means forclutching and declutching the crank shaft to the axles, pump cylindersmounted on said housing, pistons operating in said cylinders, meansconnecting said pistons to the crank shaft, said cylinders having intakeand exhaust passages, intake and exhaust valves for said intake andexhaust passages, cams on the crank shaft for the operation of saidvalves, an intake crank shaft to the axles, pump cylinders mounted l onsaid housing, pistons operating in said cylinders, means connecting saidpistons to the crank shaft, said cylinders having intake and exhaustpassages, intake and exhaust valves for said intake and exhaustpassages, cams on the crank shaft for the operation of said valves, anintake fiuid pipe connected to the intake passages,`an exhaust pipeconnected to the exhaust passages, a cylinder having series ci portsconnected to the exhaustpipe, a valve operating in the last-namedcylinder for controlling said ports, a fourth cylinder mounted on saidhousing, a stem for said valve and extending into the fourth cylinder, apiston connected to said stem, a spring acting on the last-named'pistonfor positioning the valve to open the ports of the second-namedcylinder, and hydraulic means connected to the fourth cylinder forinnuencing the piston to bring about closing of the ports by the valve.

3. In a fluid brake,v a housing rotatably supporting wheel axles-andincluding a iiuid chamber and gear chambers, a crank shaft journaled inthe fluid chamber, pairsof bevel gears located in the gear chambers andone gear of each pair of gears connected to one of the axles and theother gear connected to the crank shaft, pinions meshing with the pairsof bevel gears, drums supporting said pinions and.v the lattersupporting saiddrums about' and spaced from the pairs fil) to the crankshaft, and having intake `and ex-I haust means inI communication withthe uid chamber, and hydraulically operatedmeans for controlling theescape of fluid from the exhaust means.

LESTER H. PELSTER. 5 Y

